1. Field of the Invention
The present invention relates to a surface polishing apparatus for highly smoothly polishing the surfaces of semiconductor wafers, wafers with semiconductor-IC covered with insulator films, wafers with metal wirings, magnetic disks, glass substrates, and other plate-shaped work pieces.
2. Description of the Related Art
Recently, surface polishing apparatuses described in Japanese Patent Laid-open Publication Nos. Hei4-33336, Hei5-69310, and Hei5-309559 have been utilized to polish semiconductor wafers, magnetic disks, etc.
FIG. 8 shows an example of the conventional surface polishing apparatuses similar to that in the above-mentioned patent publications. The present surface polishing apparatus presses a work piece 132, using a pressure-retainer plate 133, into contact with the upward processing surface of a disk-shaped polishing tool 131 which is driven rotationally, to polish the surface of the work piece 132 as supplying abrasive slurry 134 to the processing surface.
The above-mentioned conventional polishing apparatus, however, generates clogging in the processing surface as time passes in polishing, resulting in a deterioration in the polishing rate (ie., amount of polishing/time) and fluctuations in the amount of polishing for each work piece. Moreover, the abrasive slurry has to be drained each time a work piece is polished, increasing the running cost.
To overcome these problems, the present applicant has invented such a surface polishing apparatus as described in Japanese Patent Laid-open publication No. Hei 8-192361. The present surface polishing apparatus, which presses a work piece into contact with the processing surface of a rotationally-driven disk-shaped polishing tool in order to polish the processing surface as supplying abrasive slurry to the processing surface, is provided, on the backward side of the work piece with respect to the rotation direction of the above-mentioned polishing tool, with an abrasive slurry-supply mechanism which supplies abrasive slurry to the above-mentioned processing surface and also, on the forward side in rotation of the work piece, with an abrasive slurry-suction mechanism which sucks and recycles the abrasive slurry drained from the above-mentioned processing surface. The present apparatus, to improve the suction efficiency, has a brush mounted on the abrasive slurry-suction mechanism, so that the brush may turn up polish chips etc. existent in depressions in the processing surface.
In practice, however, despite its remarkable effects that the conventionally apparatuses do not have, the apparatus according to the present invention still cannot sufficiently eliminate clogging in the processing surface. That is, in contrast to the case where a lower pressure is applied to the work piece, in the case of a higher pressure, more clogging may develop.